Acoustic ceiling construction



1954 v. JACOBSON 2,667,667

ACOUSTIC CEILING CONSTRUCTION Filed Nov. 5, 1948 5 Sheets-Sheet lVJacobsan fin afar A 01mg v. JACOBSON 2,667,667 ACOUSTIC CEILINGCONSTRUCTION 5 Sheets-Sheet 2 Feb. 2, 1954 Filed Nov. 5, 1948 1954 v.JACOBSON 2,667,667

ACOUSTIC CEILING CONSTRUCTION iled Nov. 5, 1948 5 Sheets-Sheet 3 V zfz 02265012 enfor Q, y I W ,iiorney Feb. 2, 1954 v JACQBSON 2,667,667

ACOUSTIC CEILING CONSTRUCTION iled Nov. 5, 1948 5 Sheets-Sheet 4 7:Jacobson orney Feb. 2, 1954 v. JACOBSON ACOUSTIC CEILING CONSTRUCTION 5Sheets-Sheet 5 iled Nov. 5, 1948 Patented Feb. 2, 1954 ACOUSTIC CEILINGCONSTRUCTION Victor Jacobson, New York, N. Y., assignor, by mesneassignments, to Level-Line Ceilings, -Inc.,

New York, N.

FL, a corporation ofNew York Application November 5, 1948, Serial No.58,439

3 Claims.

This inventionrelates to ceiling constructions and more particularlyito.those of acoustic'corr'e'ctive nature,.the invention having for itsprincipal object to provide a ceilingconstruction' which can be readilyand quickly erected at a cost which is less than heretofore possible.

Another object of .the' invention is to provide a suspendedceilingwherein the total of the exposed-surfacearea-of the sound absorptivematerial is considerably less'than the areas heretofore tho'ughtnecessary to accomplish the same degree of acoustic correction.

Another object of the invention resides inan acoustical ceilingcomprising primary and secondary supporting members, the secondarymembers having portions extending'through to and forming a part of theexposed surface of ceiling.

A further object of the invention is to provide for the installation ofacoustical tile, mechanically suspended, as distinguished fromheretofore known and usual types of ceilings depending for theirsecurernent upon nailing, cementing, screwing and the like.

A still further object of the invention is to provide a ceiling thetotal of the exposed surface area of which comprises a combination ofdifferent sound dissipating materials, one material functioning byfriction of the sound waves received, andthe other material functioningby diaphragmatic action caused by the impingement of the sound wavesthereon, these materials hereinafter referred to generally as beingsound absorptive and sound reflective.

Other objects and-advantages'of the invention will become apparent froma study of the following description and-the'drawings of a preferredembodiment of the invention.

With these and" other objects in View the invention resides in the noveldetails of construction and combinations of parts as will be disclosedmore fully hereinafter and particularly covered by'the claims.

Referring to the accompanying drawings forming a part of thisspecification and in which ilke numerals designate like parts in all theviews- Fig. 1 is a diagrammatic representation of the appearance of aceiling made in accordance with this invention and showing alternatestrips of sound-absorptive and sound reflective material;

Fig. 2 is a partial perspective view of a ceiling suspensionincorporating the elements comprising'this invention;

Fig 3 is-a vertical sectionalview taken transverselyof th'e'alternatedstripslof absorptive and reflective materials, and illustrating theirsuspension from a primary ceiling structural member;

Fig. 4 is a perspective View of a splicer utilized to align two abuttingpans constituting thesound reflective medium employed in the ceiling;construction;

Fig. 5 is a detail view partly in section illustrating the securement ofthe sound absorptivema'terial by a clip bar with respect to the pans ofsound reiiective material;

Fig. 5 is a perspective view of a modified form of hanger for suspendingthev pans of soundireflective material from aprimary ceilingstructuralmember;

Fig. 7 is a partial perspectiveview of a reinforcing strip for the buttjoint between adjacent blocks of sound absorptive material;

Fig. 8 is a detail sectionalview of a butt joint illustrating theapplication thereto of the reinforcing strip shown in Fig. 7

Fig. 9 is a perspective view'of a suspension clip for use with a clipbar at a butt joint between adjacent blocks of soundabsorptive'material;

Fig. 10 is a vertical sectionalview of a butt joint with the suspension.clip of Fig. 9 applied thereto;

Fig. 11 is a partial perspective View of' a strip of finish mouldingtobe applied at the joint between the ceiling and a vertical wall surfaceof a room;

Fig. 12 is a vertical sectional view through the finish moulding andillustrating its coaction with a block of. sound absorptive material;

Fig. 13 is a view similar to Fig. 12 but illustratzing the coactionbetween the finish moulding. and a pan of sound reflectivematerial.

Fig. is is a partial perspective viewof a ceiling suspension generallysimilar to that shown in Fig. 2, but incorporating a combined spreaderbar and reinforcing strip which performs the. functions of thestructures shown in Figs. 2, 5, 7 and 8;

Figs. 15 and 16 are respectively. a foreshortened top plan view, and aforeshortened side elevationa1 view, of the combined spreader bar andreim forcing strip; and

Fig. 17 is a verticalv transverse sectional view of the strip, said Viewbeing taken as onv thev line il -ll of Fig. 16 and looking in thedirection of the arrows.

Acoustical correction material has been proposed heretofore for ceilingsand walls, said material for best advantages being cheaply andsatisfactorily formed in sheets or blocks: of morexor less. looselycompacted'fibers. of vegetable and/or cellulosic material, resulting inmyriada of irregular cells, interstices, or openings communicating withthe exterior surfaces, into which cells or openings sound waves mayenter and be substantially completely absorbed through friction so thatsaid waves will become dissipated, thereby rendering a room extremelyquiet as compared to a room the ceilings and walls of which are not sotreated for acoustical correction. In some instances the exposed surfaceportion of the locks of acoustical material has been purposely providedwith mechanically drilled relatively large openings or cells for betterpenetration and entrapment of the sound waves within the block. It is tobe understood that according to this invention there may be employed anysatisfactory acoustical material which has the characteristic offrictionally absorbing sound waves, though preferably such acousticalmaterial should be formed in sheets or blocks of relative rigidity forease in handling and application to the wall or ceiling.

Also, in acoustical treatment of a room, there has been proposed theutilization of material which is sound reflective rather thanabsorptive, the benefit and advantage of the sound reflective materialbeing due to the fact that the impingement of the sound waves thereonsets up diaphragmatic action or vibrations in the material chiefly dueto the relative thinness of said material. These said vibrations change,modify, damp and/or otherwise affect the amplitude and/or rhythmic pulseof the original sound waves whereby the reflected sound waves are notharmonious therewith and hence counteract if not nullify the originalsound waves to render the treated room more quiet. Here again latitudeis desired in the selection of the sound refiective material thoughmetal of extreme thinness, bent into the shape of a pan, has been foundextremely practical and hence is preferred for its fire resistance andstrength.

Heretofore, acoustical correction has comprised the application ofmaterial of the same kind to substantially the entire room surface, andchief of the acoustical materials is a product identified and sold inthe building construction market under the trade-mark Acousti-Celotexwhich is made as a fibrous deposition in blocks, of the order of 12" x12" dimensions and/or multiples thereof, in various thicknesses even upto approximately 1 These blocks, however, have required nailing to studsor furring strips, requiring considerable time and labor expense intheir application, and it is an object of this invention to do away withthis costly construction of a ceiling, for example, by making possiblethe sliding of such blocks into position with their sole support uponflanges of secondary supporting members of the ceiling, which secondarymembers are in turn suspended or hung on the primary members of theceiling, thereby doing away entirely with nailing operations. Obviouslythis improvement in ceiling construction is also advantageous whenrepairs are necessary. The secondary ceiling members comprise themetallic pans or channels having sound reflective but vibratorycharacteristics, and these members have portions which extend through toand are exposed to the room area for receiving the sound waves thereon,said portions lying substantially in the plane of the exposed ceilingarea and having the appearance of strips interposed between andseparating the parallel rows of abutting blocks of sound absorbingmaterial, such as Acousti-Celotex.

In Fig. 1 is depicted diagrammatically the appearance of a ceiling madein accordance with this invention, wherein the side walls of the roomare indicated by the numeral 2, the strips 3 representing the exposedsurfaces of the pans of sound reflective material, the numeralrepresenting the ceiling area composed of rows of abutting blocks ofsound absorptive material. The widths of the pan strips 3 may be made asdesired, even up to the order of 7%" where the width of the exposed areaof the rows of sound absorptive material is of the order of 11 this panwidth having been found by experiment to be substantially the maximum inthis combination of acoustical materials for practical results. In caseswhere exceptional noise is to be corrected, the total of the exposed pansiu'faces may be lessened to thereby relatively increase the total ofthe exposed area of the sound absorptive material in the ceiling as awhole. This may be done in several ways for example, as by providingpans of lesser Width while retaining the same width of fibrous block, orby utilizing the same 7% inch width of pan with blocks of greatermultiple Width (24" width for example). A generally true statement isthat the relationship of the width of the fibrous blocks to the width ofthe pans may be changed or made to vary by virtue of the fact that thecentering of the pans can be so located as to provide for an acousticaltile or block 12 in width, or 24 in Width, and so forth, depending uponwhatever performance may be required to meet the existing condition ofnoise. Per unit of exposed surface, the cost of the sound absorptivematerial is greater than the cost of the sound reflective material, andtherefore by this invention the cost of a complete ceiling may bematerially reduced by the use of the less expensive sound reflectivematerial.

In Fig. 2 there is indicated at 5 a primary ceiling structural member(of which there may be many in the complete ceiling), which member asshown comprises a metallic channel having its web 6 disposed verticallyand the parallel flanges 1 and 8 disposed horizontally. At spacedintervals, hangers indicated generally at 9 and iii are fitted over theuppermost flange 1, each hanger having an inverted U-shaped portion H atits middle which closely fits the width of said flange, the opposite endportions of the hanger comprising angularly disposed legs such as I2with upwardly directed hook-like bends 13 at their extremities forengaging a metallic sound reflective pan generally identified by thenumeral 14, so that said pan substantially contacts the outer surface ofthe lowermost flange 8 of the structural member 5 (see Fig. 3).

Each pan is bent or pressed out of thin metallic sheet material insubstantially channel shaped formation as clearly shown in Fig. 2, thebottom or web portion thereof being indicated at 15 and adapted to liein the plane of the exposed surface of the ceiling, the oppositeparallel flange portions it and il extending vertically upward andconnected to the web portion l5 by the oppositely and outwardlyextending bends l8 and 15 respectively, which bends constitute shelvesor shoulders upon which may be seated the side edges of the blocks suchas 2i! of the sound absorptive material. The broken line 2| indicatesthat the width of the pan may be made as desired, though preferably allpans will be made of a uniform or standard width, and variations inceiling performance will be accomplished by altering the centering ofthe pan rows, i, e.

To'correctlyposition or space a pansuch as M" from thenext adjacent pansuch as wand thus in'sure theretentioni of the interposed blocks 2%! of"sound absorptive material; there isprovideda plurality ofspacedclipbars such as 25. Each clipbar is of'she'et material and maybesuitably reinforced as bya" central impressed rib' the opposite ends ofsaidb'ar being downwardly and inwardly bentv as clearlyshown' at 21- inFig.5" to form a hook-like edge" to engage under the complement'allyformed'hookdike edge 22 of the flange such'as lB'of a pan such as M,this snap engagement being permitted by the yi'eldable springiness'ofsaidbar; sound absorptivematerial down on the shelf or shoulder portionsuch'as IQ of said pan, an edge portion of the clip bar adjacent oneendthereof has a tongue 28 struck downwardly from the general plan ofsaid bar, the extremity of said tongue preferably being curled orrounded as indicated at 29 to smoothly engage the upper surface of thefiber" block 29', and adjacent the oppositeend ofsaid bar but preferablyin the opposite-edgeportion thereof, a similar tongue tifmay be formed;

The pans will be made in appropriate lengths wherefore it maybe possiblethat a plurality of pans'will be required, with their ends in abutmentwith eachoth'er; to make up one of the strips or rows shown at 3 in Fig;l separating two adjacent r'owsof fiber blocks of sound absorbingmateriall In such case, and for the pleasing appearance of the finishedceiling it willbe advisable to insure the abutting pans be- 4inginplanarregistry with each other, and to this end a splicer,generally identified by the numeral and'such as-illustrated in Fig. 4,is employed. This splicer ispreferably though not necessarily made of"the same thin gauge of sheet metal'as the pans, and is'formed'ofchannel-shaped transversesection providing the web portion 35and twoparallelupwardlyext'ending flange portions 31 and 38; the transversedimension of the splicer being such asto closely fit within the flangesof the pans; as indicated in Fig. 3;

To facilitate the correct positioning of the splicer, the upper edgeportionsof the flanges thereof-are provided at their median points withoutwardlyextendihg tabs such as 39 and is which preferably may beformed'by vertical cuts and deflection of the material (on one side ofthe out) out'of the plane of the flange, all as clearly illustrated;Thus it is only necessary to slide the splioerinto one end ofa-pan-section until said tabs strike the end edge of the pan, andthenslide the next pan section over the protruding end oi": the splicerand tap itup into abutting relation with the first pan section, saidtabs-yielding in an inward direction to permit the abutment of the twopans; due to the relative thinness of the sheet metal from which thesplioer is-made.

Two modifications ofthe pan hangers are illustratediniFigs. 3' and 6, inthe latter the hanger comprising a wire formation the middle portionof'which is'formed' of inverted U- shape-providing thetwo'parallelportions 46 and 47 and the-oppositely inclined downwardly di- To holdthe block 29 of vergent' leg portions 48' and 49 respectively, all" ofwhich are in-a commonvertical plane The end portions of the'legs arebent upwardlylat'erally and angularly as indicated at 50 to com--pleinentally engage the'angularly' bent edge p'or-- tion such as'22 of aflange of a pan. This con-- struction is common in both modifications orthe hanger. The difference in-the modificationslies in the extreme endformationof the hangers, the hanger of Fig. 6 having theext-reme endsadditionally bent as indicated at 5| to provide coaxial portionswhich-will smoothly fit andb'ein surface contact with the inner surfaceof the' hook-like bend of the edge portion of thepan flange, whereas inthe other modification shown in-Fig. 3 the extreme ends do not have thisadditional coaxial end formation and'thus said ex' treme ends terminatewith the angular bend such as 50, and hence are sharply capable ofbiting into the surface of the pan flange.

The dimension of a block 20 in a direction parallel to the adjacentsupporting pans, may be variable, and it is contemplatedhavingaplurality of blocks filling the space between two such adjacentpans, said plurality of blocks being in end abutting relation with eachother. Any suitable formation may be givento these abutting ends; inFigs. 8 and 10 there is indicated complemental rabbeted or ship-lapformations as between the abutting blocks 20 andil. Since a standardl2'- x 24" fibrous block or tile could be employed with either of itsdimensions spanning the space between the two adjacent supporting pans,it is possible. that one of such blocks might sag Withrespect to its adjacent block and thus provide an unsightly appearance to the finishedceiling. Therefore. it is contemplated providing a metallic reinforcingstrip is such as indicated in Figs. '7 and 8, and/or a suspension clipSI such as illustratedin Figs. 9 and 10, to insure planar registrationof the abutting blocks at all times.

The reinforcing strip be is formed of thin sheet metal to provide avertically disposed web-portion 62 the edge portions of which are benttwo parallel horizontally disposed flange portions 83 and er, thespacing between said flanges being substantially equal to thethicknessof the tongue portion 65 of the rabbeted edge of the block 29. In otherwords, said tongue is adapted to fit closely between said flanges asclearly shown in Fig. 8, and the vertical web portion 62 of the stripand the lower flange 64 thereof are adapted to fit closely within therabbet of the next ad- J'acent block. A tab 66, preferably'of triangularshape, is struck out of either the web 82 or the flange E4 and bentlaterally of the strip toassume a position substantially in the planexofsaid flange, wherefore the point ofsaid tab may readily enter thematerial of block 2! at its approximate center and constitutes, meansfor insuring planar registration'of the abutting ends of blocks 26 andEl. Thestrip 60 may be made of a length to fit between the flanges oftwo adjacent pans and may be provided with a suitable number of tabs foraccomplishing" the dcsired result, only one tab being illustratedv inFig. 7 in the interest of simplicity of drawing.

The suspension clip 5! has a vertical web por tion with a horizontallower flange H, and two oppositely extending upper flanges 72 and 73whose outer end portions are bent upwardly and inwardly to terminate inhook-like edges "14 and 75 respectively, adapted to springoverand engagethe oppositeedge portions of a cl-ip bar 25, wherefore this suspensionclip is intended for use where the ship-lap joint between adjacentblocks 2i] and 2: underlies a clip bar. Out of the web it any suitablenumber of tabs such as iii are struck and bent to lie substantially inthe plane of the lower flange TI. This clip may be of any suitablelength, and one or more may be provided in the row of blocks between twoadjacent pans, the clip being applied to the shiplap joint between theblocks as clearly illustrated in Fig. 10 with the tabs it pressed intothe body of the block 2! and the flange "H supporting the tongue portionof the other block 28.

Where the ceiling joins a vertical wall, there may be provided a stripof finishing moulding generally identified by the numeral til in orderto support the pans and/or the fiber blocks in the area of the wall, aforeshortened perspective view of such a finishing strip being shown inFig. 11. This strip is formed of sheet metal bent to provide thevertical wall-engaging flange 8| and the horizontal ceiling-supportingflange 82, the edge of the latter being turned over or rolled to form asmooth bearing surface 83 for the supported block or pan. These stripsmay be of any suitable length and each is provided in the flange portion8i thereof with a plurality of apertures 8 which preferably areelongated vertically as shown in order to provide adjustability whensecuring said strip to the wall 85 as by the nails 86 shown in Figs. 12and 13. To hold the pan or fiber block in contacting engagement with thesupporting flange 8'2, said strip is provided with a tongue secured atits upper end to the wall flange 31 in any con- 1 venient manner, thelower end of said tongue preferably being rounded as shown at St toprovide a smooth bearing surface against the pan or block with which itis adapted to engage. Thus the tongue may be pressed out of the wailflange 8| or may be secured thereto by soldering or spot welding, thelatter being indicated in Fig. 11 by the numeral 39. As shown in Figs.12 and 13 it may be necessary to break or cut a block or pan in order toprovide symmetry of design at the wall areas of the ceiling, but theconstruction of the strip of finish moulding takes care of thisnecessity and hides any broken or cut edges.

In Figs. 14 to 17 there is illustrated a modiflca tion of the ceilingsuspension where there is incorporated a combined spreader bar andreinforcing strip which performs the functions of the structures shownin Figs. 2, 5, '7 and 8. This suspension comprises a plurality of spacedrigid structural members such as the member 5 here tofore described, andto which the sound reflective secondary members are attached by thehangers 45 particularly illustrated in Fig. 6, the subsidiary members ofthis ceiling suspension comprising a plurality of blocks of soundabsorbing material mainly supported by underlying portions of thesecondary members.

The secondary members comprise a plurality of pans such as 95 and 95parallelly spaced from each other and. substantially of the generalformation of the pans heretofore described in that each has the bottomor web portion l5 and the opposite upwardly extending or vertical andparallel flange portions 96 and I! joined to the web portion to form theoutwardly extending bends l3 and I9, which bends constitute shelves orshoulders upon which may be seated the side edge portions of the blocksof sound absorptive material. However, in this modified construction theuppermost edge portion of the flanges is formed with an ogee or S-shapedbend as shown, in order to provide a rounded extreme edge portion 9?(see Figs. 14 and 16) for additional longitudinal reinforcing, and forsmoothly engaging the combined spreader bar and reinforcing strip, theends of a hanger 45 engaging said bend.

The combined spreader bar and reinforcing strip is shown in detail inFigs. 15, 16 and and is generally of an inverted T shape. In a practicaland economically produced form, it comprises a strip of sheet metal bentto provide a longitudinally extending central vertical web 98 (of doublethickness as shown) and two oppositely extending horizontal flanges 99and Hit. The web is of a length substantially equal to the distancebetween a vertical flange of one pan and the vertical flange of the nextadjacent pan, but each horizontal flange of this combined spreader barand reinforcing strip is extended beyond said web and bent upwardly andoutwardly to form a hook by means of which said strip is suspended fromthe upper edge portion of a pan flange.

That is to say, the horizontal flange 99 of said strip is extended andbent upwardly at one of its ends to form a vertical hanger plate IEII,the end portion of said plate being outwardly and downwardly bent toform the hook H32 adapted to overlie the upper edge portion of thevertical flange such as H of a pan (see Fig. 16) and springingly engagethe rounded extreme edge 9'! of said flange. The other horizontal flangewe of said strip is similarly extended, bent and formed to provide thehanger plate I03 and the hook I64, but the hooks Hi2 and its as shownare formed at opposite ends of said strip. Hence, when such a formedstrip or bar is in place (see Fig. 14) it serves to tie two adjacentpans (55 and 96) together and thus prevents a spreading apart thereofsuch as might cause a dislodgement of their supported blocks of soundabsorptive material. The hooks may be provided at one end only or atboth ends of each flange, and the hanger plates may be suitably securedas by welding to the web 98 to give added rigidity if desired or foundnecessary.

When using this combined spreader bar and reinforcing strip, the blocksof sound absorptive material preferably are provided on all edges withhorizontal kerfs such as Hi5 to positioned as to register with andsnugly receive therein the flanges 59 and H38 of said strip, wherebysaid blocks are reinforced by the strips, as well as additionallysupported by the flanges of the strips at the butting joint between twoadjacent blocks, thereby insuring the blocks against such saggingmovement as might result in an uneven planar registration which would beunsightly. The peripheral kerf described above permits the blocks ofsound absorptive material to be placed in either direction relative thesupporting pans. Furthermore, said strip serves to seal the jointbetween two adjacent blocks both as to ventilation and dirt (commonlyknown as breathing), and makes unnecessary the wasteful rabbeted edgeformation of the blocks as shown in Fig. 8.

From the foregoing disclosure it will thus be seen that by thisinvention there is provided an acoustic ceiling construction comprisingrigid primary supporting members such as 5, secondary members such asthe pans it suspended therefrom and having portions such as I5 lying inthe exposed surface area of the ceiling, and subsidiary members such asthe blocks 20 suspended by the underlying portions I 8, 19 of saidsecondary members, said subsidiary members having their lowermostsurface lying in the exposed surface area of the ceiling, said secondaryand subsidiary members being of material susceptible of acousticcorrection in that they are capable of disand demountable in the ceilingconstruction by virtue of such suspension. Said ceiling comprisesalternate rows such as 3 of sound reflective elements and such as 4 ofsound absorptive elements, the total of the exposed surface areas of thesound reflective elements being less than the total of the exposedsurface areas of the sound absorptive elements, and the ratio of thesetotals is limited substantially to no greater than 1 to 12 respectively.The clip bars 25, hanger springs such as 9, the splicer such as 35, thereinforcing strips such as 69, the suspension clips such as El, and thefinishing moulding such as 80 are provided as hereinabove set forth tomake a unitary whole in the ceiling.

It is obvious that those skilled in the art may vary the details ofconstruction and arrangements of parts without departing from the spiritof this invention wherefore it is desired not to be limited to the exactforegoing disclosure except as may be required by the claims.

What is claimed is:

1. An acoustic ceiling construction comprising alternate rows of soundabsorptive and sound reflective elements, the sound absorptive elementscomprising blocks of cellular material, the sound reflective elementscomprising vibratory metallic sheets formed into substantially channelshape to provide a web portion lying in the plane of the exposed surfacearea of the ceiling, and upwardly extending flange portions havinghooklike formations constituting means for suspending the soundreflective elements from a primary ceiling member, said flange portionsjoined to said web portion by bends providing laterally disposed shelvesfor supporting said blocks, and clipbars disposed over said blocks atspaced intervals. said bars having end formations complemental to andengageable with the hook-like formations of the flanges of said soundreflective elements to tie together two laterally adjacent rows of saidsound reflective elements.

2. An acoustic alterna posed surface area of the ceiling, and upwardlyextending flange portions having hook-like format-ions constitutingmeans for suspending the sound reflective elements from a primaryceiling member, said flange portions joined to said web portion by bendsproviding laterally disposed shelves for supporting said blocks, andclip-bars disposed over said blocks at spaced intervals, said barshaving end formations complemental to and engageable with the hook-likeformations of the flanges of said sound reflective elements to tietogether two laterally adjacent rows of said sound reflective elements,each clip bar having pressure means to force a block on said shelves.

3. An acoustic ceiling construction comprising alternate rows of soundabsorptive and sound reflective elements, the sound absorptive elementscomprising blocks of cellular material, the sound reflective elementscomprising Vibratory metallic sheets formed into substantially channelshape to provide a web portion lying in the plane of the exposed surfacearea of the ceiling, and upwardly extending flange portions havinghook-like formations constituting means for suspending the soundreflective elements from a blocks, and clip-bars disposed over saidblocks at spaced intervals, said bars having end formations complementalto and engageable with the hook-like formations of the flanges of saidsound reflective elements to tie together two laterally VICTOR J ACOBSONReferences Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,931,713 Walper Oct. 24, 1933 1,974,819 Koerner Sept. 25,1934 1,998,423 Stubbs Apr. 16, 1935 2,090,043 Heerwagen Aug. 17, 19372,099,211 Lucius Nov. 16, 1937 2,101,952 Olsen Dec. 14, 1937 2,121,213Small June 21, 1938 2,270,268 Chambers Jan. 20, 1942 2,307,653 WrightJan. 5, 1943 2,357,560 Taforo, Jr. Sept. 5, 1944 FOREIGN PATENTS NumberCountry Date 577,402 Great Britain May 16, 1946

